Ballast member for reducing active volume of a vessel

ABSTRACT

A ballast member may be disposed within a vessel to reduce an active volume of the vessel through which the working fluid can circulate. For instance, a solar power system may include a solar receiver through which a working fluid can be circulated and at least one solar collector that is operative to direct solar energy toward the solar receiver to heat the working fluid. A tank is fluidly connected with the solar receivers such that the working fluid can be circulated through the tank. The tank includes an internal chamber and at least one ballast member within the internal chamber that reduces the active volume of the internal chamber.

BACKGROUND

This disclosure relates to power plants for generating electricity.

Solar power plants for capturing solar energy and generating electricity are known and used. For instance, a solar collector system may direct solar energy toward a central receiver that includes a heat-absorbing fluid, such as a molten salt. The heated fluid may then be used to produce steam and drive a turbine to generate electricity. The heat-absorbing fluid may be stored in or circulated through one or more tanks.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

FIG. 1A illustrates an example solar power system.

FIG. 1B illustrates a tank from the solar power system of FIG. 1A.

FIG. 2 illustrates an example ballast member.

FIG. 3 illustrates another example ballast member.

FIG. 4 illustrates another example ballast member.

FIG. 5 illustrates an arrangement of a plurality of ballast members.

FIG. 6 illustrates another example solar power system.

FIG. 7 illustrates an example nuclear reactor system that includes a ballast member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1A illustrates selected portions of an example solar power system 20 for capturing and using solar energy 22. Although selected components of the solar power system 20 are shown in this example, it is to be understood that additional components may be utilized with the solar power system 20 to generate electricity in a known manner, for example.

The solar power system 20 includes a solar receiver 24 through which a working fluid 26 can be circulated. For instance, the working fluid 26 can be circulated through pipelines 28 (i.e., conduit) or other suitable conduits for handling the particular type of working fluid 26. As an example, the working fluid 26 may be a molten salt, such as potassium nitrite and sodium nitrite. These salts may be solid at ambient temperatures and pressures but may be molten or liquid at the operating temperatures of the system. Depending upon the type of system used, the working fluid 26 may alternatively be another type, such as water, oil, liquid metal or a fluoride salt, or even a mixture of compatible working fluids. Given this description, one of ordinary skill in the art will recognize suitable working fluids 26 to meet their particular needs.

The solar power system 20 includes at least one solar collector 30 (three shown) that is operative to direct the solar energy 22 toward the solar receiver 24 to heat the working fluid 26 in a known manner. As an example, the solar collector 30 may include one or more heliostats for tracking and following the sun.

The solar receiver 24 may include a trough-type solar collector or other type of solar collector that is known for receiving the solar energy 22 and transferring heat to the working fluid 26. It is to be understood that the solar power system 20 may be modified from the illustrated example and include other types of solar collectors 30 and solar receivers 24.

A tank 32 (i.e., a vessel) is fluidly connected with the solar receiver 24 via the pipeline 28 or other conduit. In this case, the working fluid 26 may be temporarily held in the tank, circulated into the tank 32, or circulated from the tank 32, for example. Thus, the working fluid 26 generally is circulated through the tank 32, although the circulation may or may not be continuous. The tank 32 may therefore be considered to be a storage tank.

The tank 32 includes an internal chamber 34 for holding or circulating the working fluid 26. At least one ballast member 36 is disposed within the internal chamber 34 to reduce the fillable or active volume of the internal chamber 34 through which the working fluid 26 can be circulated. Thus, the ballast member 36 may be regarded as any material that takes up or reduces the fillable volume of the internal chamber 34 such that less working fluid 26 can be used in the system along with a reduced burden on filtering or purifying high volumes of the working fluid 26. In some examples, the ballast member 36 serves the sole purpose of reducing or taking up the fillable volume of the internal chamber 34 and does not actively serve any other function within the solar power system 20. In other examples, the ballast may act as a thermal storage mechanism, as well as a volume reduction device.

FIG. 1B illustrates a cross-sectional view of the tank 32 showing a fill level 38 of the working fluid 26. In this case, the tank 32 includes an outlet 39 a through which the working fluid 26 leaves the tank 32, and a return inlet 39 b through which the working fluid 26 enters the tank 32. The ballast member 36 takes up at least a portion of the fillable volume of the internal chamber 34 such that the fill level 38 is above the return inlet 39 b. In this case, given the same amount of working fluid 26 within the tank 32, the fill level 38 would be below the return inlet 39 b if the ballast member 36 were not present, as shown at 38′. Thus, the ballast member 36 enables control over the level of the working fluid in the tank 32 by reducing the fillable volume of the internal chamber 34. In this regard, the level can be controlled such that the return inlet 39 b is below the fill level 38 of the working fluid 26. This provides the benefit of having the returned working fluid 26 flow directly into the working fluid 26 that is already in the tank 32 rather than dropping from a point above the fill level 38. Such an arrangement facilitates avoiding turbulence of the working fluid 26 and in entraining air or other gas within the working fluid 26 from turbulence. In a further example, the return inlet 39 b may be a ring sparger (i.e., a loop with a plurality of nozzles/holes) located at the bottom of the tank 32 to introduce the working fluid 26. Additionally, the tank 32 can have “dead space” with regard to the amount of working fluid 26 participating in the solar power system 20. Reducing the fillable volume of the internal chamber 34 reduces the dead space such that less of the working fluid 26 can be used. Thus, as can be appreciated, the ballast member 36 could be used in any type of vessel to reduce the fillable volume of the vessel. In this regard, the ballast member 36 may alternatively be located within the pipelines 28, such as the jumper piping of a trough-type solar energy system, a manifold of the system, or any other fluid-handling vessel.

FIG. 2 illustrates an example ballast member 136 that may be used in the tank 32. The ballast member 136 is designed to withstand the expected temperatures and conditions within the tank 32. For instance, the working fluid 26 may be at a relatively high temperature compared to the ambient surroundings and may be corrosive to many types of materials. In this example, the ballast member 136 is generally an elongated rod and, in the illustration, is sectioned to reveal the interior.

The ballast member 136 includes a sealed shell 140 and a core material 142 disposed within the interior volume of the sealed shell 140. The sealed shell 140 may have closed-off ends such that the interior volume is sealed from the surroundings and the working fluid 26 is unable to flow into the interior volume. The closed-off ends may be welded ends or caps that are welded or sealed. Alternatively, the ends of the shell 140 may be crimped to seal off the shell 140.

The ballast member 136 is essentially immobile and inert. For instance, the ballast member 136 cannot move within the tank 32 to plug up the outlet 39 a or return inlet 39 b. Additionally, the ballast member 136 is chemically unreactive with the working fluid 26 and thereby does not degrade the working fluid 26 or form byproducts from any reactions with the working fluid 26.

In the illustrated example, the sealed shell 140 has a tubular shape, which provides the benefit of easy packing, manufacturing, and minimizes stress concentrators. However, the sealed shell 140 may alternatively have another type of shape or geometry that is suitable for the intended use within the tank 32.

The sealed shell 140 may be formed of a material that is suitable for withstanding the expected temperatures and corrosion conditions within the tank 132. For instance, the sealed shell 140 may be formed of steel or stainless steel. In some examples, steel or stainless steel may be used when the working fluid 26 is potassium nitrite/sodium nitrite or liquid metal (e.g., sodium or potassium). In other examples where the working fluid 26 may be a more corrosive material, such as a fluoride salt, the sealed shell 140 may be formed from a nickel-based alloy, superalloy, or ceramic material. In some examples, the sealed shell 140 may be an alloy based on nickel, cobalt, nickel-iron, or alloy containing chromium to resist the corrosive conditions. Alternatively, the sealed shell 140 may be a composite of the disclosed types of shell materials or include a ceramic outer shell that extends around an inner shell of an alloy material.

The core material 142 is generally formed of a high heat capacity material. In some examples, the core material 142 is a refractory material, such as a gunning mix, that can be preformed (e.g., cast) and then placed into the sealed shell 140 prior to sealing. The gunning mix may include aluminate and other refractories, as are generally known. Alternatively, or in addition to a refractory, another type of core material 142 may be used, such as sand, gravel, mine tailings, dirt, combinations thereof, or other material having a high heat resistance. In a further example, the core material 142 may be dry or dried prior to inclusion within the sealed shell 140 to facilitate reducing the presence of any gaseous water within the sealed shell 140 at the expected elevated temperatures. As an example, the core material 140 may have a moisture content of less than 5 wt % or even below 1 wt %.

The core material 142 serves the purpose of adding weight to the ballast member 136 such that the ballast member 136 is not buoyant in the selected working fluid 26. Thus, a relatively inexpensive type of material may be used and robust properties aside from the heat capacity may not be required.

In this example, the core material 142 is formed into the shape of a cylinder that fits within the internal volume of the sealed shell 140. In this case, an expansion gap 144 between the core material 142 and the inner diametrical surface of the sealed shell 140 allows for thermal differences in expansion/contraction of the sealed shell 140 and the core material 142.

FIG. 3 illustrates a modified example of a ballast member 236. In this case, the ballast member 236 also includes the sealed shell 140. However, the ballast member 236 includes core material 242 that is granular. As an example, granules of the core material 242 may be packed into the internal volume of the sealed shell 140 before sealing off the ends. The material selected for the core material 242 may be the same as described relative to FIG. 2.

FIG. 4 illustrates a modified example of another ballast member 336. In this example, the ballast member 336 also includes the sealed shell 140. However, the ballast member 336 includes a core material 342 that includes a plurality of elongated rods 346 that are packed within the interior volume of the sealed shell 140. The elongated rods 346 may have a cylindrical shape and extend unidirectionally within the interior volume. The elongated rods 346 may be formed of the same materials as described relative to the previous examples and then inserted into the sealed shell 140 before sealing off the ends. The ballast member 336 may further include a granular material in between the elongated rods 346, which may be used to modify ballast density and/or thermal storage capability.

FIG. 5 illustrates a plurality of the ballast members 136 in a stacked arrangement. The stacked arrangement may then be disposed within the tank 32 as the ballast member 36. Although the ballast members 136 are shown in this example, it is to be understood that the ballast members 236 or 336 may alternatively be used in such an arrangement. In this case, the cylindrical shape of the ballast members 136 formed gaps 60 between neighboring ballast members 136. In operation, the working fluid 26 may flow through the gaps 60. In some cases, the working fluid 26 may include solid debris and the gaps 60 may facilitate trapping the solid debris among the ballast members 136 such that the ballast members 136 effectively function as a filter to purify the working fluid 26. The stacked arrangement shown may be oriented horizontally within the tank 32. It is to be understood however, that the ballast members 136 may alternatively be oriented vertically or in any other desired orientation.

In a modified example, the arrangement may also include one or more screens 62 (shown schematically) that extends between at least two of the ballast members 136 and further facilitates trapping any solid debris within the gaps 60. As shown, the screen is arranged near the ends of the ballast members 136 but alternatively may be provided along the sides or along the sides and ends.

FIG. 6 illustrates another example solar power system 120 that is somewhat similar to the solar power system 20 of FIG. 1. In this example, the solar power system 120 includes a hot tank 132 a and a cold tank 132 b for holding and/or circulating the working fluid 26. Depending on the system and the type of working fluid 26 that is used, the hot tank 132 a may operate at a temperature of approximately 1100-1800° F. (approximately 593-982° C.). The cold tank 132 b may operate at temperatures of as low as about 500° F. (260° C.). For an oil system, the hot tank 132 a may operate at a temperature of around 750-800° F. (approximately 400-427° C.) and the cold tank 132 b may operate at a temperature of around 72° F. (approximately 22° C.).

In this case, the working fluid 26 is heated within the solar receiver 24 and circulated into the hot tank 132 a. Pumps 70 may be used to circulate the working fluid 26 through the pipeline 28 or other type of conduit. The working fluid 26 circulates through an electric generator 72 for generating electricity in a know manner. As an example, the electric generator 72 may include a heater 74, a steam turbine 76, and a condenser 78.

In operation, the heated working fluid 26 flows through the heater 74 to heat another working fluid, such as water. The vaporized water powers a steam turbine 76 that turns a shaft in a known manner to generate electricity. The steam is collected and then condensed in the condenser 78 before returning to the heater 74 for another cycle.

The working fluid flows from the heater 74 into and through the cold tank 132 b. The relatively cooler working fluid 26 may then be provided from the cold tank 132 b to the solar receiver 24 for another cycle of use. As can be appreciated, other components may be used in combination with the illustrated components to facilitate or enhance operation of the solar power system 120.

FIG. 7 illustrates another example application of the ballast member 136, although any of the ballast members 236 or 336 disclosed herein may be used. The ballast member 136 is located within a nuclear reactor system 400 that utilizes liquid metal as the working fluid 26. Alternatively, the nuclear reactor system 400 may be a different type that utilizes a different working fluid.

The nuclear reactor system 400 is generally of a known arrangement and includes, for instance, a reactor vessel 432 that houses a reactor core 433 for receiving nuclear control rods 435. A plenum 437 divides the internal chamber 434 into a hot section (H) containing the core 433 and a cold section (C) outside of the core 433.

The reactor vessel 432 operates in a known manner to heat a second working fluid contained within an electric generator system 472 of the nuclear generator system 400. The second working fluid may be used to drive a turbine 476 to in turn generate an electric current.

In the illustrated example, a support structure 439 supports the ballast member 136 within the reactor vessel 432. For instance, the support structure may be a rack or other suitable structure that may be attached to the reactor vessel 432 for holding and immobilizing the ballast member 136. That is, the support structure 439 limits movement of the ballast member 136 such that flow of the working fluid 26 within the reactor vessel 432 does not cause the ballast member 136 to shift position and interfere with other components in the reactor vessel 432. The support structure 439 also enables the ballast member to be mounted in a desirable location within the reactor vessel 432, such as near a side wall of the reactor vessel 432 in the cold section (C). Locating the ballast member 136 in the cold section (C) facilitates reducing the exposure of the ballast member 136 to the elevated temperatures present of the hot section (H) that may otherwise be detrimental to the longevity of the sealed shell 140. It is to be understood that the support structure 439 may also be used in the other examples disclosed herein.

Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments or other systems than solar power systems and nuclear power systems. That is, other types of heat transfer systems or systems utilizing working fluids may benefit from the disclosed examples.

The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art and do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can be determined by studying the following claims. 

1. A solar power system comprising: a solar receiver through which a working fluid can be circulated; at least one solar collector operative to direct solar energy toward the solar receiver to heat the working fluid; and a tank fluidly connected with the solar receiver such that the working fluid can also be circulated through the tank, the tank including an internal chamber and at least one ballast member within the internal chamber that reduces an active volume of the internal chamber through which the working fluid can circulate.
 2. The solar power system as recited in claim 1, wherein the at least one ballast member includes a sealed shell having an interior volume and a core material disposed within the interior volume.
 3. The solar power system as recited in claim 2, wherein the sealed shell includes a corrosion resistant material.
 4. The solar power system as recited in claim 3, wherein the corrosion resistant material is a ceramic material.
 5. The solar power system as recited in claim 3, wherein the corrosion resistant material is an alloy.
 6. The solar power system as recited in claim 2, wherein the sealed shell comprises a tube.
 7. The solar power system as recited in claim 2, wherein the core material comprises a refractory material.
 8. The solar power system as recited in claim 7, wherein the refractory material comprises aluminate.
 9. The solar power system as recited in claim 7, wherein the refractory material is a granular material.
 10. The solar power system as recited in claim 2, wherein the core material is selected from a group consisting of sand, gravel, mine tailings, dirt, and combinations thereof.
 11. The solar power system as recited in claim 2, wherein the core material has a moisture content of less than 5 wt %.
 12. The solar power system as recited in claim 7, wherein the core material comprises at least one elongated rod.
 13. The solar power system as recited in claim 1, wherein the at least one ballast member includes a plurality of ballast members arranged with gaps therebetween.
 14. The solar power system as recited in claim 13, further comprising a screen extending between at least two of the plurality of ballast members.
 15. The solar power system as recited in claim 1, wherein the volume of the at least one ballast member is such that a level of the working fluid within the tank is above a return inlet into the tank.
 16. A solar power system comprising: a solar receiver through which a working fluid can be circulated; at least one solar collector operative to direct solar energy toward the solar receiver to heat the working fluid; a hot tank fluidly connected to receive the heated working fluid from the solar receiver; a electric generator fluidly connected to receive the heated working fluid from the hot tank; a cold tank fluidly connected to receive the working fluid from the electric generator, the hot tank and the cold tank including respective internal chambers and respective ballast members within the internal chambers that reduce an active volume of the internal chambers through which the working fluid can circulate.
 17. The solar power system as recited in claim 16, wherein the ballast members each include a sealed shell having an interior volume and a core material disposed within the interior volume, and the sealed shell is a corrosion resistant material.
 18. The solar power system as recited in claim 17, wherein the corrosion resistant material is a ceramic material.
 19. The solar power system as recited in claim 17, wherein the corrosion resistant material is an alloy.
 20. The solar power system as recited in claim 16, wherein the ballast members each comprise a plurality of elongated ballast members arranged with gaps therebetween.
 21. The solar power system as recited in claim 20, wherein the ballast members each comprise a plurality of ballast members and a screen extending between at least two of the plurality of ballast members.
 22. The solar power system as recited in claim 16, wherein the electric generator includes a heater, a steam turbine and a condenser operative to circulate water that is heated by the working fluid.
 23. A method for controlling a working fluid in a solar power system, comprising: circulating a working fluid through an internal chamber of a tank that is fluidly connected with a solar receiver that receives solar energy from at least one solar collector to heat the working fluid; and controlling a fill level of the working fluid in the tank by disposing at least one ballast member within the internal chamber of the tank to reduce an active volume of the internal chamber through which the working fluid can circulate.
 24. The method as recited is claim 23, further including removing debris from the working fluid using a screen that is attached to the at least one ballast member.
 25. A vessel comprising: a working fluid disposed within the vessel, the working fluid being selected from a group consisting of liquid salt, oil, liquid metal, fluoride salt and mixtures thereof; and at least one ballast member disposed at least partially within the working fluid.
 26. The vessel as recited in claim 25, wherein the at least one ballast member includes a sealed shell having an interior volume and a core material disposed within the interior volume.
 27. The vessel as recited in claim 26, wherein the sealed shell includes a corrosion resistant material.
 28. The vessel as recited in claim 27, wherein the corrosion resistant material is a ceramic material.
 29. The vessel as recited in claim 27, wherein the corrosion resistant material is an alloy.
 30. The vessel as recited in claim 26, wherein the sealed shell comprises a tube.
 31. The vessel as recited in claim 26, wherein the core material comprises a refractory material.
 32. The vessel as recited in claim 31, wherein the refractory material comprises aluminate.
 33. The vessel as recited in claim 31, wherein the refractory material is a granular material.
 34. The vessel as recited in claim 26, wherein the core material comprises at least one elongated rod.
 35. The vessel as recited in claim 25, wherein the at least one ballast member includes a plurality of ballast members arranged with gaps therebetween.
 36. The vessel as recited in claim 35, further comprising a screen extending between at least two of the plurality of ballast members.
 37. The vessel as recited in claim 25, wherein the vessel is a conduit, a tank, or a reactor.
 38. The vessel as recited in claim 25, further comprising a support structure supporting the at least one ballast member and limiting movement thereof within the working fluid. 